Implement the following plan:

Reorganize reuse into subpackages by concern

Currently all code lives in one flat reuse package. Move parsers into public subpackages, matching the internal/core + type alias pattern used by manifests and registries.

Problem: import cycles

Root package (project.go) imports subpackages. Subpackages need ReuseInfo, SourceType, PrecedenceType from root. That's a cycle.

Fix: move shared types to internal/core. Root re-exports them as type aliases (type ReuseInfo = core.ReuseInfo). Subpackages import internal/core directly. No cycles.

Target structure

reuse/
  reuse.go               type aliases from internal/core, package docs
  project.go             Project, OpenProject, ReuseInfoOf, AllReuseInfo
  project_test.go
  covered.go             IsCoveredFile, CoveredFiles, IsIgnoredDir, IsIgnoredFile
  covered_test.go
  internal/
    core/
      core.go            ReuseInfo, SourceType, PrecedenceType (actual definitions + methods)
  extract/
    extract.go           ExtractReuseInfo, ExtractFromFile, FilterIgnoreBlocks
    extract_test.go
  dep5/
    dep5.go              Dep5, ParseDep5, ParseDep5File, ReuseInfoOf
    dep5_test.go
  toml/
    toml.go              ReuseTOML, Annotation, ParseReuseTOML, ParseReuseTOMLFile, ReuseInfoOf
    toml_test.go
    glob.go              GlobMatch (only used by toml, stays here)
    glob_test.go

What moves where

• reuse.go types/constants/methods -> internal/core/core.go
• reuse.go becomes type aliases + package doc
• extract.go + test -> extract/ subpackage, package extract, imports internal/core
• dep5.go + test -> dep5/ subpackage, package dep5, imports internal/core
• toml.go + test -> toml/ subpackage, package toml, imports internal/core and uses alias for BurntSushi/toml (btoml)
• glob.go + test -> toml/ subpackage (glob is only used by toml matching)
• covered.go + test -> stays in root (no deps on subpackages, no cycle risk)
• project.go + test -> stays in root, imports extract, dep5, toml subpackages

Import paths after reorganization

Consumer usage:

Changes to each file

internal/core/core.go (new)

• All types, constants, methods from current reuse.go
• package core

reuse.go (rewrite)

• Package doc stays
• Type aliases: type ReuseInfo = core.ReuseInfo, type SourceType = core.SourceType, etc.
• Constant re-exports: const (FileHeader = core.FileHeader; ...)

extract/extract.go

• Change package reuse -> package extract
• Import github.com/git-pkgs/reuse/internal/core
• Replace ReuseInfo with core.ReuseInfo, FileHeader with core.FileHeader

dep5/dep5.go

• Change package reuse -> package dep5
• Import github.com/git-pkgs/reuse/internal/core
• Same type replacements

toml/toml.go

• Change package reuse -> package toml
• Import btoml "github.com/BurntSushi/toml" (alias to avoid name conflict with package name)
• Import github.com/git-pkgs/reuse/internal/core
• Same type replacements

toml/glob.go (moved from root)

• Change package reuse -> package toml
• No other changes needed

project.go

• Add imports for extract, dep5, toml subpackages
• Replace direct function calls: ExtractFromFile -> extract.ExtractFromFile, etc.
• Replace ParseReuseTOMLFile -> toml.ParseReuseTOMLFile
• Replace ParseDep5File -> dep5.ParseDep5File
• Types stay as ReuseInfo etc. since root re-exports them

covered.go

• No changes (no deps on moved code, only uses stdlib)

Tests

• Each test file moves with its source, changes package name
• assertSlice helper is duplicated into each test package (or made a shared test helper)
• mkfile helper stays in root test (project_test.go, covered_test.go)
• extract_test.go and dep5_test.go each get their own assertSlice

Verification

1. go build ./...
2. go test -v -race ./...
3. go vet ./...
4. Confirm 64 tests still pass across all packages

If you need specific details from before exiting plan mode (like exact code snippets, error messages, or content you generated), read the full transcript at: /Users/andrew/.claude/projects/-Users-andrew-code-git-pkgs/e29c14b3-41b4-4a33-a3ba-dc32811240a3.jsonl